Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753505AbdIDJPJ (ORCPT ); Mon, 4 Sep 2017 05:15:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:57629 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753333AbdIDJPI (ORCPT ); Mon, 4 Sep 2017 05:15:08 -0400 Date: Mon, 4 Sep 2017 11:15:05 +0200 From: Michal Hocko To: Xishi Qiu Cc: Andrew Morton , KAMEZAWA Hiroyuki , Reza Arbab , Yasuaki Ishimatsu , Igor Mammedov , Vitaly Kuznetsov , linux-mm@kvack.org, LKML Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Message-ID: <20170904091505.xffd7orldpwlmrlx@dhcp22.suse.cz> References: <20170904082148.23131-1-mhocko@kernel.org> <20170904082148.23131-3-mhocko@kernel.org> <59AD15B6.7080304@huawei.com> <20170904090114.mrjxipvucieadxa6@dhcp22.suse.cz> <59AD174B.4020807@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <59AD174B.4020807@huawei.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1368 Lines: 37 On Mon 04-09-17 17:05:15, Xishi Qiu wrote: > On 2017/9/4 17:01, Michal Hocko wrote: > > > On Mon 04-09-17 16:58:30, Xishi Qiu wrote: > >> On 2017/9/4 16:21, Michal Hocko wrote: > >> > >>> From: Michal Hocko > >>> > >>> We have a hardcoded 120s timeout after which the memory offline fails > >>> basically since the hot remove has been introduced. This is essentially > >>> a policy implemented in the kernel. Moreover there is no way to adjust > >>> the timeout and so we are sometimes facing memory offline failures if > >>> the system is under a heavy memory pressure or very intensive CPU > >>> workload on large machines. > >>> > >>> It is not very clear what purpose the timeout actually serves. The > >>> offline operation is interruptible by a signal so if userspace wants > >> > >> Hi Michal, > >> > >> If the user know what he should do if migration for a long time, > >> it is OK, but I don't think all the users know this operation > >> (e.g. ctrl + c) and the affect. > > > > How is this operation any different from other potentially long > > interruptible syscalls? > > > > Hi Michal, > > I means the user should stop it by himself if migration always retry in endless. If the memory is migrateable then the migration should finish eventually. It can take some time but it shouldn't be an endless loop. -- Michal Hocko SUSE Labs